Chestnut Oak (Quercus prinus), so named due to the resemblance of its leaves to the American Chestnut, is also called Rock Oak, Rock Chestnut Oak, or Mountain Oak, as it is often found in dry, rocky soils at the tops of hilly ridges. Chestnut Oak is also listed by some authorities with the scientific name of Quercus montana.
In Ohio, it is confined to the eastern half of the state, mostly in the Appalachian highlands. Nationally, it ranges on either side of a line from southern Maine to western Tennessee, encompassing the greater Appalachian area. It survives where other trees do not, in areas of dry, barren soils (often a companion to Scarlet Oak and Black Oak in these environments). Its dark green leathery leaves, large acorns, stout twigs, thick bark with triangular ridges, and jagged winter outline give it an exceptionally bold texture. It may reach 60 feet tall and 50 feet wide when located in the open. As a member of the White Oak group and the Beech Family, it is related to the Beeches, Chestnuts, and other Oaks.
Chestnut Oak achieves its greatest growth on moist, well-drained soils of acidic pH. However, it is usually found growing in poor, rocky, sterile, dry soils of acidic pH where it can compete with the tough site conditions and win. It also adapts to soils of neutral or alkaline pH. It thrives in full sun to partial sun (but is shade tolerant in youth), and is found in zones 4 to 8.
Chestnut Oak is amazingly free of major pest and disease problems, a testament to superior genetics in all aspects of its growth cycle. However, it may on occasion be subject to the usual array of pests and pathogens that can affect many Oaks.
Chestnut Oak has leaves that are alternate, obovate, with wavy crenate margins.
As in the similar-appearing leaves of Swamp White Oak, leaf shape is somewhat variable in terms of how shallow or deep the spaces are between the crenations, but unlike Swamp White Oak, the leaf undersides are medium green, rather than white.
Chestnut Oak is monoecious, having pollen-bearing catkins in mid-spring that fertilize the inconspicuous female flowers on the same tree. Since it is a member of the White Oak group, the fruits (acorns) only take a single season to develop. Chestnut Oak along with Swamp Chestnut Oak, Swamp White Oak, and English Oak is known for the long penduncles that attach to its shiny acorns, which ripen in early to mid-autumn.
The terminal buds of Chestnut Oak are pointed and large. Its twigs are stout, and its branches quickly accumulate thick fissured bark.
The growth habit of Chestnut Oak is rounded and dense through middle age, then becomes more wide-spreading with greater maturity.
Its mature bark is different than any other Oak, having ridges that are triangular in cross-section, with deep furrows in-between. Even with age, Chestnut Oak retains the light gray to medium gray color of its bark that is characteristic of the White Oak group.